Funky's, Cranky's and Swanky's mini-games:
Enter Extras as a password.

50 more lives:
Enter Monkey as a password.

No DK and Star-Barrels in new game:
Enter Tuffer as a password.

Disable midpoint barrels:
Enter harder as a password.

Reach Krematoa
To reach Krematoa (the Lost World), go to the four rocks east [Left] of Mekanos. Stay on the rocks as you circle around it clockwise about four times and the volcano will replace the rocks.